The Development Of Measuring And Controlling System Of Torque Rheometer Based On RS-485 Bus

The torque rheometers are ideal instruments to study properties of polymer material such as flowing, plastication and shearing stability, which have been applied to the scientific research and technical development. By introducing distributed monitor and control and RS-485 communication technologies into torque rheometers to develop distributed measuring and controlling system, the stability of system is improved greatly, the maintainment and extension of instruments become easier.The designing idea, hardware achievement and software designing of measuing and controlling system were expounded in this paper. The system is simple, hardware is excellent, software is powerful, and interface is friendly.The measuing and controlling system of torque rheometer developed in this paper was a distributed control system which took computer as core. Devices communicated on RS-485 bus. Modbus communication protocol guaranteed that data were transmited reliably, truly and quickly. Some parameters such as temperature, pressure and torque were respectively measured by temperature module, pressure and torque module. Microcontroller was the core of these modules. Rotate speed was measured by PLC. They composed the hardware of system. In order to improve the measuement precision of pressure, the ratio measurement theory was adopted. The software comprise main controller part and inner softwares of lower devices. The main controller software had friendly interface, was convenient and powerful. It included user interface module, lower devices corresponding module, Modbus communication module. The inner program of temperature module and pressure and torque module was designed by C51 in lower devices. The inner control program of PLC was designed by ladder language to measure rotate speed and accomplish other functions.The tests indicated that torque rheometer designed had excellent performances and could meet demand.